Interface and related method for connecting sensor equipment and a physiological monitor

ABSTRACT

An interface to connect sensor equipment and a physiological monitor includes a first connector to receive power from a first channel of the monitor and a second connector to receive power from a second channel of the monitor. The power from each of the first and second channels of the monitor is combined within the interface. The interface further includes a third connector to provide the combined power to the sensor equipment; a voltage converter to rescale the voltage of the combined power that is provided to the sensor equipment; and a scaling circuit to reduce the voltage of a signal representing a measured physiological parameter. The signal representing the measured physiological parameter is sent from the sensor equipment to the monitor. The interface is advantageous to allow sensor equipment to be sufficiently powered by a monitor that would not typically provide enough power.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 13/801,870, filed Mar. 13, 2013, the entire contents of all of whichare incorporated herein by reference.

BACKGROUND

The present invention relates generally to an interface for connectingsensor equipment to a monitoring system.

Various physiological parameters of a patient are monitored during manymedical procedures. These physiological parameters may be bloodpressure, temperature, rate-of-fluid flow, or other vital signs thatprovide the physician or medical technician with critical informationrelated to the status of a patient's condition.

One device that is widely used to monitor physiological parameters isthe blood pressure sensor. A blood pressure sensor is often included ina sensor guide wire for intravascular measurements. The blood pressuresensor senses a patient's blood pressure and provides a representativeelectrical signal that is transmitted to the exterior of the patient.For most applications, the sensor must be electrically energized. Totransmit energy and the signal representative of the patient's bloodpressure, thin electrical leads are often provided inside the guidewire. The guide wire is generally in the form of a tube (e.g., having anouter diameter of 0.35 mm), which is often made of stainless steel.

Monitoring systems are used in a medical environment to receive andprocess information related to the patient's physiological parameters. Asensor (e.g., a blood pressure sensor) may be directly connected to amonitor of the monitoring system via a sensor guide wire. Alternatively,the sensor may be connected to the monitor via a receiver or otherintermediary device. In one embodiment utilizing a receiver, the sensorguide wire sends a wireless signal to the receiver, which is directlyconnected to the monitor. The monitor typically includes a channel usedto connect the sensor equipment (e.g., the sensor guide wire or thereceiver) to the monitor. Through this channel, the sensor equipment maybe powered by the monitor.

SUMMARY

The BP22 standard (ANSI/AAMI BP22: 1994/(R)2006) (referred to herein as“BP22”) governs performance and safety requirements for transducers,including cables, designed for blood pressure measurements. Inparticular, the connection between sensor equipment and physiologymonitors is governed by the BP22 standard. Many currently existingmonitors include channels that comply with the BP22 standard. Suchmonitors can provide power larger than or equal to 80 mW. However,certain monitors do not have channels that comply with the BP22standard, and these monitors may not be able to provide sufficient powerto sensor equipment connected to the monitor. In other circumstances,even if the monitors generally comply with the BP22 standard, the sensorequipment may require more power than the monitor can provide.

According to one exemplary embodiment of the present invention, aninterface to connect sensor equipment and a monitor includes a firstconnector to receive power from a first channel of the monitor and asecond connector to receive power from a second channel of the monitor.The power from each of the first and second channels of the monitor iscombined within the interface. The interface further includes a thirdconnector to provide the combined power to the sensor equipment; avoltage converter to rescale the voltage of the combined power that isprovided to the sensor equipment; and a scaling circuit to reduce thevoltage of a signal representing a measured physiological parameter. Thesignal representing the measured physiological parameter is sent fromthe sensor equipment to the monitor.

According to another exemplary embodiment, a method for connectingsensor equipment and a monitor includes combining a power signal from afirst channel of the monitor and a power signal from a second channel ofthe monitor to form a combined power signal; resealing the voltage ofthe combined power signal; providing the combined power signal to thesensor equipment; and adapting the voltage of a signal representing ameasured physiological parameter, which is sent from the sensorequipment to the monitor.

Alternative exemplary embodiments relate to other features andcombinations of features as may be generally recited in the claims.

BRIEF DESCRIPTION OF THE FIGURES

The disclosure will become more fully understood from the followingdetailed description, taken in conjunction with the accompanyingfigures, wherein like reference numerals refer to like elements, inwhich:

FIG. 1 is a schematic diagram of a medical system for measuringphysiological parameters, according to an exemplary embodiment.

FIG. 2 is a circuit diagram representing a circuit to connect sensorequipment to a monitor, according to an exemplary embodiment.

FIG. 3 is a circuit diagram representing a circuit to connect sensorequipment to a monitor, according to another exemplary embodiment.

FIG. 4 is a circuit diagram representing a circuit to connect sensorequipment to a monitor, according to yet another exemplary embodiment.

FIG. 5 is a schematic representation of a cable containing a circuit toconnect sensor equipment to a monitor, according to an exemplaryembodiment.

DETAILED DESCRIPTION

Before turning to the figures, which illustrate exemplary embodiments indetail, it should be understood that the invention is not limited to thedetails or methodology set forth in the description or illustrated inthe figures.

Referring to FIG. 1, a system for measuring physiological parametersaccording to an exemplary embodiment includes a sensor wire 2, areceiver 4, and a monitor 6. “Sensor equipment” may include either orboth of the sensor wire 2 and the receiver 4, as well as any other typeof sensor equipment that a user may desire to connect to a monitor forreceiving and processing information related to physiologicalparameters. For example, sensor equipment can include equipment used tomeasure any number of physiological parameters, such as ECG, SpO₂,non-invasive blood pressure, invasive blood pressure, temperature, orcardiac output. The sensor wire 2 or the receiver 4 may be connected tothe monitor 6 to receive power from the monitor 6 using various circuitsdescribed herein.

The monitor 6 is part of a monitoring system for receiving, processing,and outputting information related to the patient's measuredphysiological parameters. The monitor 6 can be any monitor that haschannels for direct connection of sensor equipment (e.g., a sensor wire2 or a receiver 4). In FIG. 1, the monitor 6 includes pressure channelsfor sensor equipment used to measure a patient's aortic blood pressure(P1) and distal blood pressure (P2). In one embodiment, the monitor 6 isthe GE CARESCAPE MONITOR B650, produced by GE HEALTHCARE. The GECARESCAPE MONITOR B650 is described in manuals that can be found on GEHEALTHCARE's website, for example at:http://www.gehealthcare.com/siteplanning/docs/B650%20cut%20sheet.pdf.Information accessible through the GE HEALTHCARE website and related tothe GE CARESCAPE MONITOR B650 on the filing date of this patentspecification is hereby incorporated by reference herein in itsentirety.

In one embodiment, the sensor wire 2 is connected to a pressuretransducer 8, which is used to measure the patient's aortic bloodpressure. The sensor wire 2 conveys information related to the patient'saortic blood pressure, as measured by pressure transducer 8, to themonitor 6. A common procedure for measuring aortic pressure is toconnect a pressure transducer 8 to a guide catheter 10 located in apatient's aorta. The sensor wire 2 is directly connected to the monitor6.

The receiver 4 conveys information related to the patient's distal bloodpressure to the monitor 6. To measure distal blood pressure, the distalend of a sensor guide wire having a pressure transducer 52 (shown inFIG. 5) is inserted into the body of a patient, for example into anopening into the femoral artery, and placed at a desired location. Inone embodiment, the pressure transducer 52 measures the blood pressuredistal to a stenosis in the patient's coronary artery. Measurement ofaortic and distal blood pressure (and subsequent calculation offractional flow reserve) is a way to diagnose, for example, thesignificance of a stenosis. A transmitter 48 is electrically connectedto a sensor guide wire 50 to wirelessly transmit blood pressureinformation to the receiver 4, which is correspondingly configured toreceive wireless signals from the transmitter 48 (FIG. 5). The receiver4 is connected to the monitor 6 to transmit the blood pressureinformation to the monitor 6. In one embodiment, the receiver 4 is thePRESSUREWIRE AERIS RECEIVER developed by ST. JUDE MEDICAL. One suitablesensor guide wire is described in U.S. Pat. No. 8,187,195, which isincorporated by reference herein in its entirety for the components,systems, and methods described therein related to physiologicalmonitoring.

Some types of sensor equipment receive power from the monitor to whichthey are connected. For example, in FIG. 1, the receiver 4 may receivepower from the monitor 6. However, the channels of certain monitors arenot configured to provide sufficient power to the sensor equipment, suchas receiver 4, to allow the sensor equipment to operate as intended.These monitors may not provide sufficient power because they do notcomply with the BP22 standard or because the sensor equipment requiresmore power than the monitor is able to provide. Accordingly, variousembodiments of circuitry 14 described in connection with FIGS. 2-4provide a connection between sensor equipment 12 and a monitor 6 toallow the sensor equipment to be adequately powered by the monitor 6.The circuitry 14 can be embodied in any suitable form of hardware, suchas within a cable to connect the sensor equipment and the monitor. Thecables described herein, which contain circuitry 14, therefore serve asan interface between sensor equipment 12 and monitor 6 that allow thesensor equipment 12 to receive sufficient power from monitor 6.

Referring to FIG. 2, a circuit diagram according to an exemplaryembodiment illustrates the electrical connection between sensorequipment 12 and a monitor 6. The sensor equipment 12 may include aWheatstone Bridge 13. Traditionally, a blood pressure transducer hasconsisted of a pressure responsive diaphragm that is mechanicallycoupled to piezoresistive elements connected in a Wheatstone Bridge-typecircuit arrangement. When the diaphragm is placed in fluid communicationwith a body cavity (such as within the arterial or venous system),pressure induced deflections of the diaphragm cause the resistiveelements to be stretched (or compressed, depending on theirorientation). According to well-known principles, this alters theresistance of the elements in a manner that is related to the appliedpressure. The magnitude of the applied pressure can thus be detected byapplying an excitation power signal (usually in the form of a voltage)to the inputs of the Wheatstone bridge circuit, and by simultaneouslymonitoring the bridge output signal. The magnitude of that signalreflects the amount by which the bridge resistance has changed,according to Ohm's law.

Typically, an electrical cable connects the Wheatstone bridge portion ofthe transducer sensor to a transducer amplifier circuit contained withinthe vital signs monitor, such as the monitor 6 shown in FIG. 1. Channelsof the monitor 6 (e.g., for the connection of sensor equipment via acable) are illustrated in FIG. 2 as first channel 16 and second channel18. The amplifier circuit within monitor 6 supplies the excitation powersignal to the Wheatstone bridge, and simultaneously monitors the bridgeoutput signal. The excitation power signal is typically in the form of avoltage and, depending on the monitor type and manufacturer, can havevarying magnitudes and formats, both time-varying (sinusoidal,square-waved and pulsed) and time independent (DC). According to theprinciples under which conventional Wheatstone-bridge transducersoperate, transducer amplifier circuits in most patient monitors havebeen designed to expect a sensor output signal having a magnitude thatis proportional to the magnitude of the excitation power signal and alsoproportional to the magnitude of the sensed pressure.

Referring again to FIG. 2, circuitry 14 connects the sensor equipment 12to a monitor (such as the monitor 6 shown in FIG. 1). The circuitry 14can be included within a cable that can be connected to multiple portsof a monitor 6. In conventional connections between sensor equipment anda monitor, a cable connects the sensor equipment to a single channel ofthe monitor. However, the cable 44 or other physical interface thatincludes circuitry 14 connects to two channels of the monitor 6 (seeFIG. 5). Accordingly, the cable 44 or other physical interface has afirst connector 40 and a second connector 42, shown schematically inFIG. 5. Although shown in separate housings, the first connector 40 andsecond connector 42 can be contained within a single housing thatprovides two connections to the monitor 6. The first connector 40 can beoperatively coupled to the first channel 16 of monitor 6 to receive anexcitation power signal from monitor 6. Similarly, the second connector42 can be operatively coupled to the second channel 18 to receiveanother excitation power signal from monitor 6. At least one of thechannels (e.g., first channel 16) receives a signal representing ameasured physiological parameter from the sensor equipment via one ofthe connectors (e.g., first connector 40). For example, in FIG. 2, aconnector operatively couples to the first channel 16 in order to allowtransmission of: 1) an excitation signal from the monitor 6 to thesensor equipment 12, and 2) a signal representing the measuredphysiological parameter from the sensor equipment 12 to the monitor 6.The cable 44 (FIG. 5), which includes circuitry 14, therefore providesan interface that allows the sensor equipment 12 to obtain power fromtwo channels of a monitor 6, rather than one. This feature allows sensorequipment 12 to be used with monitors 6 that do not provide sufficientpower through a single channel to operate the sensor equipment 12 (e.g.,for use with monitors that do not comply with the BP22 standard or withsensor equipment that requires more power than a monitor can provide).

As noted above, monitor 6 includes a first channel 16 and a secondchannel 18. In the embodiment of FIG. 2, the first channel 16 bothreceives a signal from the sensor equipment 12 and provides anexcitation power signal in the form of a voltage. The voltages providedby the channels 16, 18 are represented as V_(ex) in FIGS. 2-4. Thesignal lines transmitting the pressure or other signals representingphysiological parameter(s) to the monitor 6 are represented in FIGS. 2-4as “S.” The second channel 18 of the monitor 6 provides an additionalexcitation power signal to the sensor equipment 12. The excitation powersignals from the first channel 16 and the second channel 18 of themonitor 6 are combined within circuitry 14 prior to being supplied tothe sensor equipment 12. By combining the power from two channels of themonitor 6, a cable that includes circuitry 14 allows sensor equipment 12to be used with monitors that would not provide sufficient power througha single channel. In one embodiment, the power supplied by each channel16, 18 is 50 mW. If the sensor equipment 12 requires 80 mW, sufficientpower can be obtained by using both channels 16, 18 (which would providea total of 100 mW).

Circuitry 14 further includes one or more filters 20 a, 20 b to limitnoise. The filters can be passive filters, active filters, or any othertype of suitable filter. A DC to DC converter 22 rescales the voltagesupplied by the monitor 6 to the sensor equipment 12. In one embodiment,the voltage is resealed because the sensor equipment 12 requires ahigher voltage to operate than is provided by the monitor 6. In oneexample, each channel 16, 18 provides 2.5V, and the sensor equipment 12requires 4-8V and 20 mA to operate. The DC to DC converter 22 thereforeincreases the voltage from 2.5V to a voltage between 4-8V. In oneembodiment, the converter 22 is a voltage doubler that increases thevoltage from 2.5V on the input side to 5.00V on the output side.

Once the sensor equipment 12 has been used to measure one or morephysiological parameters, such as blood pressure, the signalrepresenting the measured physiological parameter is transmitted througha scaling circuit 24. Scaling circuit 24 adapts the voltage. In oneembodiment, scaling circuit 24 reduces the voltage, and in yet anotherembodiment the scaling circuit 24 is a voltage divider. The scalingcircuit 24 can include resistors or any other combination of componentsthat adapts the voltage difference between the S+ and S− signal lines.The voltage is adapted by scaling circuit 24 because the monitor 6 isconfigured to receive a certain voltage (e.g., 2.5V) from the sensorequipment 12. For example, the monitor 6 may be configured to receive12.5 mV for each millimeter of Hg of pressure. In the example describedabove in which each channel provides 2.5V and the sensor equipmentrequires 4-8V to operate, the converter 22 doubles the voltage providedto sensor equipment 12. Scaling circuit 24 therefore halves the voltagein order for the monitor 6 to accurately convert the received signal toa physiological parameter measurement (e.g., to a blood pressuremeasurement). In one embodiment, the monitor 6 assumes that theimpedance of the sensor equipment 12 is high enough not to load theexcitation voltage (e.g., 2.5V). Thus, the monitor 6 expects to receivea signal having a voltage directly related to the excitation voltage(e.g., 2.5V) from the sensor equipment 12. If the sensor equipment 12 isconfigured to return a signal representing blood pressure, the monitor 6monitors the difference between the S+ and the S− signal lines andconverts the difference to a corresponding pressure reading. Byresealing the voltage provided to the sensor equipment 12 and thenadapting the return signal, the circuitry 14 provides an interface thatallows the sensor equipment 12 (e.g., a receiver 4) to be supplied witha sufficient voltage while ensuring that the monitor 6 can accuratelyconvert the return signal to a physiological parameter measurement(e.g., a blood pressure measurement).

Referring to FIG. 3, a circuit diagram illustrates an additionalexemplary embodiment of an electrical connection between sensorequipment 12 and a monitor 6. Similar to the embodiment of FIG. 2,circuitry 14 serves as an interface between sensor equipment 12(including a Wheatstone Bridge 13) and a monitor 6. Circuitry 14combines the power excitation signals from a first channel 16 and asecond channel 18 to provide sufficient power to the sensor equipment12, allowing the sensor equipment 12 to be used with monitors that maynot provide sufficient power through a single channel.

The circuitry 14 of FIG. 3 includes a scaling circuit 26 to modify thesignal from the sensor equipment 12 to the monitor 6. The scalingcircuit 26 scales the signal from the sensor equipment 12 to a constantsensitivity. In one embodiment, the scaling circuit 26 includes avoltage-controlled amplifier 28 and a capacitor 30; however, othercircuits that use a reference voltage to scale, such as anADC-microcontroller-DAC construct, may be used. The scaling circuit 26also includes components to accomplish the same functions as scalingcircuit 24, described in connection with FIG. 2. In other words, scalingcircuit 26 scales the signal to a voltage interpretable by theparticular monitor 6. The function of scaling the signal provided to themonitor 6 can be accomplished by using one or more scaling circuitscontaining a variety of different components.

The inclusion of scaling circuit 26 in FIG. 3 changes the requirementsrelated to the DC to DC converter 22 relative to the embodiment of FIG.2. In the embodiment of FIG. 2, the converter 22 must provide a voltagestable enough to be used by the sensor equipment 12, scaled by thescaling circuit 24, and interpreted by the monitor in a manner thatyields an accurate pressure reading (or reading of another physiologicalparameter). In other words, the FIG. 2 design (in order to be accurate)requires that the voltage doubler accurately double the voltage (e.g.,within 0.5%). However, in FIG. 3, the presence of a scaling circuit 26allows for the use of a less accurate (or less stable) converter 22because the scaling circuit 26 will adapt the signal from the sensorequipment 12 dependent on the actual voltage provided to the WheatstoneBridge 13. The signal is scaled by the scaling circuit 26 such that thesignal sent to the monitor 6 will be accurately interpreted by theparticular monitor 6. The inclusion of a scaling circuit 26 that scalesbased on the actual voltage applied to the Wheatstone Bridge 13therefore allows the use of a less precise (cheaper) converter 22.

FIG. 4 illustrates a still further exemplary embodiment of theelectrical connection between sensor equipment 12 and a monitor 6. Inthis embodiment, circuitry 14 allows a user to choose (e.g., via aswitch 32) whether the signal received by the monitor 6 is scaled basedon a fixed reference level or based on the excitation voltage from firstand second channels 16, 18. As in previous embodiments, the excitationpower signals provided by the first channel 16 and the second channel 18are combined in the embodiment of FIG. 4. Filters 20 a, 20 b filternoise. Although specific filter embodiments are shown in FIG. 4, thefilters 20 a and 20 b can be passive filters, active filters, or anyother type of suitable filter. In one embodiment, one or both of filters20 a and 20 b are low pass filters. The embodiment of FIG. 4 includes aDC to DC converter 22 to rescale the input voltage. In one embodiment,the converter 22 increases the voltage, and in yet another embodimentthe converter 22 doubles the voltage. After measurement of the relevantphysiological parameter (e.g., blood pressure), the sensor equipment 12provides a signal representing the measured parameter to a third filter20 c. The filter 20 c can be active, passive, or any other type ofsuitable filter. In one embodiment, the third filter 20 c is adifferential low pass filter, which reduces signal noise.

The scaling circuit 24 of FIG. 4 includes a buffer amplifier 34. Thebuffer amplifier 34 includes a reference input 36. The switch 32 allowsa user (or manufacturer) to switch the reference input 36 from a fixedreference voltage provided by reference voltage source 38 and theexcitation voltage provided by monitor 6 (e.g., at intersection 19).When the switch 32 is in the first position (the position shown in FIG.4), the reference input 36 has a fixed voltage as a result of referencevoltage source 38. However, when the switch 32 is switched to the secondposition, reference input 36 will have a voltage equal to the excitationvoltage provided by monitor 6. Certain monitors are configured to use afixed reference to interpret the signal received from sensor equipment12. If circuitry 14 of FIG. 4 is being used to interface these monitorsto sensor equipment 12, the switch should be in the position shown inFIG. 4 such that the signal received by the monitor 6 is scaled based ona fixed reference voltage. However, other monitors are configured to usethe excitation voltage provided by the monitor as a reference by whichto interpret the signal received from sensor equipment 12. To use thecircuitry 14 of FIG. 4 with these systems, the switch 32 should be inthe second position, which enables the signal received from the sensorequipment 12 to be scaled using the excitation signal provided by themonitor as the reference voltage.

FIG. 5 illustrates a schematic diagram of a cable 44 that includescircuitry 14 according to any of the embodiments described herein. Asdescribed above, the cable 44 includes a first connector 40 and a secondconnector 42 that can be operatively coupled to the first and secondchannels 16, 18, respectively, of a monitor 6. The connectors 40, 42allow excitation power signals to be transmitted from the monitor 6 tothe cable 44, through circuitry 14 contained within cable 44, and to thesensor equipment (such as receiver 4). The connectors 40, 42 furtherallow a signal representing a measured physiological variable to betransmitted from the sensor equipment, through circuitry 14, and to themonitor 6. In one embodiment, the signal representing a measuredphysiological variable is transmitted via connector 40 to the monitor 6.As shown in FIG. 5, the cable 44 further includes a third connector 46.The third connector 46 can be operatively coupled to the sensorequipment, such as a receiver 4, to transmit power from the monitor 6 tothe sensor equipment. The receiver 4 may receive informationrepresenting measured blood pressure from a transmitter 48, which isconnected to a sensor wire 50 having a pressure transducer 52. In oneembodiment, the sensor wire 50 is a PRESSURE WIRE AERIS™ developed byST. JUDE MEDICAL.

Several advantages arise from using the circuitry 14 described herein.In effect, circuitry 14 provides an interface that allows a monitor toprovide sufficient power to sensor equipment. This feature may bedesirable if the monitor does not comply with the BP22 standard or ifthe sensor equipment requires more power than a single channel of themonitor can provide. Circuitry 14 combines available monitor channels,each providing an excitation power signal, to achieve the total powerand voltage required by the connected sensor equipment. Circuitry 14(e.g., in the embodiment shown in FIG. 4) allows for accuratemeasurements of a physiological variable by flexible adaption of thereference voltage of a scaling circuit. Circuitry 14 may also enhancethe accuracy of a sensor measurement by stabilizing the power supply tothe connected sensor equipment and normalizing sensor sensitivity to theinterface.

The construction and arrangement of the systems and methods as shown inthe various exemplary embodiments are illustrative only. Although only afew embodiments have been described in detail in this disclosure, manymodifications are possible (e.g., variations in structures of thevarious elements, values of parameters, mounting arrangements, use ofmaterials, etc.). For example, the position of elements may be reversedor otherwise varied and the nature or number of discrete elements orpositions may be altered or varied. Accordingly, all such modificationsare intended to be included within the scope of the present disclosure.The order or sequence of any process or method steps may be varied orre-sequenced according to alternative embodiments. Other substitutions,modifications, changes, and omissions may be made in the design,operating conditions and arrangement of the exemplary embodimentswithout departing from the scope of the present disclosure.

What is claimed is:
 1. A cable comprising: a first connector configured to receive power from a first channel of a physiological monitor and a second connector configured to receive power from a second channel of the monitor, wherein the power from each of the first and second channels of the monitor is combined within the cable; a third connector configured to provide the combined power to a receiver configured to receive information representing a measured physiological parameter and generate a signal representing the measured physiological parameter; a voltage converter configured to rescale the voltage of the combined power that is provided to the receiver; wherein the cable is configured to receive the signal representing the measured physiological parameter that is generated by the receiver, and wherein the cable is configured to provide a signal representing the measured physiological parameter to the monitor via the first connector and/or the second connector.
 2. The cable of claim 1, wherein the first and second channels of the monitor do not comply with the BP22 standard governing excitation power signals.
 3. The cable of claim 1, wherein the cable is configured to interface with a receiver requiring more power than the first channel of the monitor is configured to provide.
 4. The cable of claim 1, wherein the measured physiological parameter is blood pressure.
 5. The cable of claim 1, wherein the voltage converter is configured to double the voltage of the combined power.
 6. The cable of claim 1, further comprising a plurality of filters configured to reduce noise.
 7. The cable of claim 1, wherein the first connector and the second connector are disposed within a single housing configured to provide two connections to the monitor.
 8. A method for connecting a receiver to a physiological monitor, comprising: using a cable, combining an excitation power signal received from a first channel of the monitor via a first connector of the cable and an excitation power signal received from a second channel of the monitor via a second connector of the cable, to form a combined power signal; using the cable, rescaling the voltage of the combined power signal; using the cable, providing the rescaled combined power signal to the receiver, via a third connector of the cable; using the receiver, wirelessly receiving information representing a measured physiological parameter, and generating a signal representing the measured physiological parameter; using the cable, receiving the signal representing the measured physiological parameter that is generated by the receiver, using the cable, providing the signal representing the measured physiological parameter to the monitor, via the first connector and/or the second connector of the cable.
 9. The method of claim 8, wherein the first and second channels of the monitor do not comply with the BP22 standard governing excitation power signals.
 10. The method of claim 8, wherein the receiver is a receiver requiring more power than the first channel of the monitor is configured to provide.
 11. The method of claim 8, wherein the measured physiological parameter is blood pressure.
 12. The method of claim 8, wherein the step of rescaling the voltage of the combined power signal includes doubling the voltage of the combined power signal.
 13. The method of claim 8, further comprising filtering the combined power signal to reduce signal noise.
 14. The method of claim 8, wherein the first connector and the second connector are disposed within a single housing configured to provide two connections to the monitor. 